254
FXUS65 KBYZ 091034
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
434 AM MDT FRI OCT 9 2026
KEY MESSAGES
- VERY WARM & DRY WITH BREEZY CONDITIONS FRIDAY WILL BE
PROBLEMATIC FOR ANY NEW OR EXISTING FIRES. RED FLAG WARNINGS IN
EFFECT FOR WESTERN FOOTHILLS, SHERIDAN COUNTY AND BIGHORN NF.
- COLD FRONT ARRIVES EARLY SATURDAY, THEN MUCH COOLER SATURDAY
NIGHT THROUGH MONDAY; THIS WILL BE THE COOLEST AIR MASS YET OF
THE FALL. MANY LOCATIONS COULD SEE THEIR FIRST FREEZE OF THE
SEASON SUNDAY NIGHT OR MONDAY NIGHT.
- STRONG WEATHER SYSTEM ARRIVES THIS WEEKEND. MOUNTAINS AND
FOOTHILLS SNOW ACCUMULATION IS LIKELY SATURDAY NIGHT TO MONDAY,
WITH RAIN AND WET SNOW AT LOWER ELEVATIONS. GREATEST POTENTIAL
FOR SNOW ACCUMULATION IS WEST OF BILLINGS. POTENTIAL IMPACTS TO
TRAVEL AND OUTDOOR RECREATION. DETAILS REMAIN VERY UNCERTAIN.
- ACTIVE WEATHER PATTERN CONTINUES THROUGH MUCH OF NEXT WEEK.
DISCUSSION
THROUGH NEXT THURSDAY...
SATELLITE IMAGERY SHOWS FLAT RIDGING OVER THE NORTHERN ROCKIES
SHIFTING SLOWLY TO THE EAST, AS A DEEP PACIFIC TROF DIGS NEAR THE
BC COAST. THE UPSTREAM TROF IS OUR WEATHER-MAKER FOR THE WEEKEND,
BUT IN THE MEANTIME WE HAVE TO DEAL WITH THE RIDGE FOR ONE MORE
DAY.
TODAY WILL BE VERY HOT AND DRY PER ENHANCED DOWNSLOPE WINDS/
WARMING IN A PRE-FRONTAL REGIME. TEMPS WILL BE IN THE 80S TO NEAR
90F AND SOME DAILY RECORDS COULD BE BROKEN. MIN RHS WILL FALL TO
NEAR OR BELOW 10% MANY AREAS, WITH THE ASSISTANCE OF BREEZY SW
WINDS WHICH WILL GUST 35-45 MPH ALONG THE WESTERN FOOTHILLS. A RED
FLAG WARNING REMAINS IN EFFECT FOR THE WESTERN AND SOUTHERN
FOOTHILLS (AREAS THAT DID NOT SEE SIGNIFICANT RAINFALL IN
SEPTEMBER AND HAVE MUCH DRIER GRASSES). TONIGHT WILL BE ANOTHER
MILD NIGHT W/ POOR RH RECOVERY. STILL LOOKS LIKE SOME MODEST
DOWNSLOPE GUSTS COULD IMPACT THE LEE SIDE OF THE BEARTOOTHS AND
BIGHORNS LATE TONIGHT AND THIS WILL NEED TO BE MONITORED. A COLD
FRONT ARRIVES EARLY SATURDAY BRINGING AN END TO THE RECENT WARM
AND DRY STRETCH OF WEATHER, FINALLY.
EXPECT BRISK NORTH WINDS AND FALLING TEMPS ON SATURDAY, ALONG WITH
INCREASING CHANCES OF SHOWERS IN THE WEST AS AN UPPER LOW FORMS
OVER THE PACNW. THE LOW WILL CONTINUE TO PUSH SOUTHWARD SUNDAY &
MONDAY, A BIT WEST OF WHAT WOULD BE IDEAL FOR PRECIP HERE, BUT THE
COMBINATION OF ASCENT, UPSLOPE FLOW AND ANOMALOUSLY HIGH
ATMOSPHERIC MOISTURE WILL YIELD A GOOD PERIOD OF PRECIPITATION.
ALL OF THIS IS OF HIGH CONFIDENCE AT THIS POINT. MOUNTAINS WILL
SEE HEAVY SNOW (60-70% CHANCE OF 12+ INCHES ABOVE 8KFT) AND A
WINTER STORM WATCH HAS ALREADY BEEN ISSUED FOR THE BEARTOOTH
ABSAROKA & CRAZY MOUNTAINS. THE HEAVY SNOW WILL LIKELY ALSO
INCLUDE THE MELVILLE FOOTHILLS ON THE EAST SIDE OF THE CRAZIES,
PER DEEP E-SE FLOW. THE BIGGER QUESTIONS CONCERN SURFACE TEMPS,
PTYPE AND WHETHER OR NOT SNOW WILL BE ABLE TO ACCUMULATE AT LOWER
ELEVATIONS.
TODAY'S MODELS HAVE TRENDED WARMER IN THE BOUNDARY LAYER AND THUS
THE POTENTIAL FOR ACCUMULATING SNOW EAST OF THE FOOTHILLS HAS
TRENDED DOWN. THE AIR MASS WE WILL TAP INTO IS CURRENTLY IN
AK/YUKON. THERE SEEMS TO BE TWO PIECES OF COLDER AIR, THE COLDER
OF WHICH IS SHOWN TO STAY IN NORTHERN CANADA WHILE THE LESSER COLD
SAGS THRU AB INTO MT. THIS SEEMS TO GIVE SOME CREDENCE TO THE
WARMER MODEL SOLUTIONS, BUT MUST ALSO STRESS CONTINUED HIGH SPREAD
AMONG ENSEMBLES. THE OTHER UNCERTAIN PIECE OF THE PUZZLE IS
MOISTURE FROM RACHEL, A HURRICANE STILL WEST OF BAJA. PWATS ARE
EXPECTED TO RISE TO NEAR 200% OF NORMAL IN OUR CWA THIS WEEKEND AS
MOISTURE IS DRAWN NORTHWARD IN THE HIGHLY AMPLIFIED SW FLOW ALOFT.
WOULD EXPECT A SURGE OF HEAVIER PRECIP OVER OUR EAST SUNDAY NIGHT
INTO MONDAY, BUT MODELS DIFFER HERE. ONE THING TO BE MORE
CONFIDENT OF IS THAT SURFACE TEMPS LOOK TO STAY SUFFICIENTLY WARM
TO KEEP PTYPE AS RAIN OVER THE EAST, BUT CANNOT RULE OUT SNOWFALL
OVER THE HIGHER HILLS. GENERALLY SPEAKING, THE HIGHEST POTENTIAL
FOR SNOW ACCUMULATION AT LOWER ELEVATIONS IS WEST OF BILLINGS. FOR
BILLINGS ITSELF, BELIEVE IT WILL SNOW BUT STRUGGLE TO ACCUMULATE,
WITH THE POSSIBLE EXCEPTION OF THE HIGHER HILLS SURROUNDING THE
CITY. SMALL TEMPERATURE CHANGES WOULD MEAN BIG DIFFERENCES IN THE
WEATHER WE SEE. THE CHANCE OF 2+ INCHES OF SNOW IS NEAR ZERO IN
THE EAST, ABOUT 10% AT BILLINGS, AND 50-80% ALONG THE WESTERN
FOOTHILLS. IMPACTS FROM ANY HEAVY SNOW WOULD INCLUDE TRAVEL,
OUTDOOR RECREATION, AND WEIGHING DOWN OF TREE LIMBS AND POSSIBLE
TREE DAMAGE. LOOK FOR TEMPS IN THE 30S & 40S SUNDAY & MONDAY.
PLEASE CONTINUE TO MONITOR THE FORECAST AS ADDITIONAL ADJUSTMENTS
WILL BE NECESSARY.
BEFORE MOVING ON WE SHOULD ADDRESS ACTUAL PRECIPITATION, WHICH
WILL BE WIDESPREAD AND SIGNIFICANT. ENSEMBLES SHOW TOTALS OF
0.25-0.50" IN THE EAST AND 1-1.5" IN THE WEST. WESTERN MOUNTAINS
COULD SEE MORE THAN THIS, AS COULD THE EAST, DEPENDING ON THE
EXACT TRACK AND IMPACTS OF RACHEL'S MOISTURE.
THE UPPER LOW WILL EVENTUALLY CUT OFF OVER THE SW CONUS AND THE
PASSAGE OF A WEAK ZONAL WAVE WILL END OUR PRECIP SOMETIME MONDAY
OR MONDAY EVENING. AFTER A DRY & WARMER TUESDAY (TEMPS IN 50S TO
NEAR 60F) THINGS GET MORE INTERESTING AGAIN. THERE IS INCREASING
CONFIDENCE THAT THE SW LOW WILL EJECT TO THE NORTH AND CLIP
SOUTHEAST MT WITH A GOOD CHANCE OF SHOWERS (RAIN) WEDNESDAY. AT
THE SAME TIME, ANOTHER CANADIAN WAVE ARRIVES AND POSSIBLY PHASES
WITH THE LOW, CONTINUING THE CHANCE OF PRECIP THROUGH THURSDAY. BY
WEDNESDAY NIGHT AND THURSDAY TEMPS COULD COOL ENOUGH FOR WET SNOW,
AND THE NORTHERLY FLOW WOULD FAVOR SOUTHERN UPSLOPE AREAS (A
DIFFERENT SCENARIO THAN THE INITIAL WEEKEND SYSTEM). EXPECT TEMPS
NEAR 60F WEDNESDAY THEN UPPER 40S AND 50S THURSDAY. JKL
AVIATION
12Z TAF/AVIATION DISCUSSION...VFR CONDITIONS WILL CONTINUE
TONIGHT THROUGH TOMORROW NIGHT. SOUTHWEST WINDS WILL INCREASE
ALONG THE WESTERN FOOTHILLS BEFORE SUNRISE, THEN BECOME GUSTY TO
STRONG AT TIMES AS THE SURFACE INVERSION MIXES OUT AROUND 16-19Z.
EXPECT W-SW WINDS GUSTING 20 TO 40KTS BECOMING WIDESPREAD,
STRONGEST OVER THE WESTERN FOOTHILLS. THE EAST SLOPES OF THE
BIGHORNS WILL SEE DOWNSLOPE WESTERLY WIND GUSTS DURING THE
AFTERNOON AND INTO THE EVENING. A COLD FRONT WILL ARRIVE AROUND
06Z TOMORROW EVENING OVER NORTHERN ZONES, SHIFTING WINDS TO THE
NORTH/NORTHEAST. AHEAD OF THE FRONT EXPECTED ANOTHER PERIOD OF
GUSTY WESTERLY WINDS FROM LATE EVENING THROUGH THE FRONTAL
PASSAGE, INCLUDING IN THE NORMALLY CALM AREA LEE OF THE BIGHORN
MOUNTAINS (KSHR). CHAMBERS
PRELIMINARY POINT TEMP/POPS
TDY SAT SUN MON TUE WED THU
-------------------------------------------------------
BIL 086 052/066 036/041 032/045 035/055 039/059 041/056
0/U 01/E 9+/O 97/O 22/W 33/W 43/W
LVM 084 047/064 030/038 027/046 027/056 030/057 030/054
0/N 18/W ++/O 96/O 22/W 23/W 54/W
HDN 088 048/069 037/048 033/049 034/059 036/061 038/057
0/B 00/B 79/R 96/R 22/W 44/W 54/W
MLS 085 050/069 041/048 037/047 037/058 041/058 041/055
0/B 00/B 69/R 97/R 12/W 45/W 44/W
4BQ 088 053/073 044/052 039/051 038/061 042/058 042/054
0/U 01/B 47/R 96/R 23/W 56/W 55/W
BHK 087 051/075 037/051 031/048 031/058 035/058 035/055
0/U 00/B 48/R 87/O 22/W 46/W 65/W
SHR 088 049/073 035/048 032/050 032/059 034/058 034/055
0/U 02/W 68/R 94/R 33/W 66/W 64/W
BYZ WATCHES/WARNINGS/ADVISORIES
MT...WINTER STORM WATCH IN EFFECT FROM SATURDAY EVENING THROUGH
LATE SUNDAY NIGHT FOR ZONES 67-68.
RED FLAG WARNING IN EFFECT FROM NOON TODAY TO 9 PM MDT THIS
EVENING FOR ZONES 117-123-124-126.
WY...RED FLAG WARNING IN EFFECT FROM NOON TODAY TO 9 PM MDT THIS
EVENING FOR ZONES 274-284.
WEATHER.GOV/BILLINGS
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